The present invention relates generally to weighing apparatus for weighing multiple packages of various shapes and sizes. More specifically, the present invention is directed to a weighing apparatus having multiple conveyors and multiple scales in a master/slave relationship for weighing a plurality of packages of various shapes and sizes.
Weighing apparatus may be used in a variety of processes. Weighing apparatus may be used as part of a conveyor system to weigh items as they travel along a conveyor. One such system, known generally as a checkweigher, may include three conveyors arranged one after the other each with a separate purpose. The first conveyor may be an infeed conveyor, the second a weighing conveyor and the third a discharge conveyor. The infeed conveyor may accelerate items to give proper spacing so that the weighing conveyor weighs one item at a time. This type of a system may not have the capacity or throughput to weigh many different sized items in a highly efficient manner.
Other weighing apparatus, such as that described in U.S. Pat. No. 5,990,422, may use multiple weighing conveyor belts. Such apparatus may use a photo eye at the entrance of each belt to detect when a package arrives on that belt. The apparatus may also use the distance between the photo eyes as a reference length to assist in determining the length of the package and to reduce error. This type of weighing apparatus may generally require complex circuitry and computation to determine the length while not eliminating error due to variations in the conveyor motor drive systems.
Exemplary embodiments of the present invention may overcome or solve these problems. Exemplary embodiments of the present invention may be directed to a weighing apparatus having a plurality of conveyor belts, a plurality of physical scales associated with the plurality of conveyor belts and a master processor electronically connected to the plurality of physical scales. The master processor may form a plurality of logical scales by combining two or more physical scales. The weighing apparatus may also include a plurality of slave processors. The slave processors may detect multiple weight samples from the physical and logical scales and may pass those samples through a filter to remove high frequency noise. The slave processors may send the results to the master processor which may compute a net weight based on the results provided by the slave processors.
The weighing apparatus may also include a single photo eye which may detect when a package arrives at the first conveyor belt. Exemplary embodiments of the present invention may not be concerned with detecting a reference length based on the distance between more than one photo eye. Exemplary embodiments of the present invention preferably use only a single photo eye so that detecting a reference length is not even possible. Using the speed of the conveyor belts and the duration of time the package is in front of the photo eye, a length of the package may be calculated. The master processor may then use the calculated length to track the package as it passes from conveyor belt to conveyor belt rather than using a second or third photo eye.